This invention is generally directed to toner and developer compositions, and more specifically the present invention is directed to toner compositions, including magnetic, single component, two component, and colored toner compositions comprised of polyesters. In one embodiment of the present invention, the toner compositions are comprised of biodegradable semicrystalline polyesters, including specifically, for example, polyhydroxyalkanoates, copolymers thereof, or blends, that is, a uniform mixture whose component parts are substantially indistinquishable thereof, and pigment particles. There is also provided in accordance with the present invention positively charged toner compositions comprised of biodegradable, that is particles that degrade, for example, under environmental conditions present in streams, landfill sites, and the like, semicrystalline polyester resin particles, pigment particles, and charge enhancing additives. Furthermore, there is provided in accordance with the present invention toner compositions comprised of biodegradable semicrystalline polyester resin particles, and optional additives, especially surface additives such as metal salts of fatty acids including zinc stearate, and colloidal silica particles such as the Aerosils. In addition, the present invention is directed to developer compositions comprised of the aforementioned toners, and carrier particles. Furthermore, in another embodiment of the present invention there are provided single component toner compositions comprised of biodegradable semicrystalline polyester resin particles, magnetic components such as magnetites, optional charge enhancing additives, and optional surface additives. The toner and developer compositions of the present invention are useful in electrostatographic imaging and printing systems, including the Xerox Corporation 1075.TM., 1065.TM., 9700.TM., and the like. The polyester toner resin compositions of the present invention are biodegradable, therefore there is enabled the facile and efficient deinking thereof, for example, from papers with developed images containing the aforementioned toners. It is believed that the semicrystalline polyester resin particles are degraded by, for example, enzymatic attack thereof by, for example, enzymes present in ground soil, and by aqueous hydrolysis. Specific semicrystalline polyesters that may be selected for the toners of the present invention, and processes for the preparation thereof are disclosed, for example, in Macromolecules (1987), 20, 3086, entitled "Synthesis of Crystalline Beta-Hydroxybutyrate/Beta-h,Hydroxyvalerate Copolyesters by Coordination Polymerization Of Beta-Lactones", and Biomaterials, 8, 289 to 295, (1987) "Polymers For Biodegradable Medical Devices", the disclosures of which are totally incorporated herein by reference. These processes, which generate synthetic products, are substantially different than the biological processes described in ICI European Patent Publication Nos. 0,052,459 and 0,069,497, the disclosures of which are totally incorporated herein by reference.
There is also provided in accordance with the present invention processes for the preparation of biodegradable semicrystalline polyesters, and processes for the preparation of toner compositions comprised of the aforementioned polyesters.
Toner compositions comprised of resin particles including styrene acrylates, styrene methacrylates, styrene butadienes, and polyesters, such as those illustrated in U.S. Pat. No. 3,590,000, are known. Also, toner compositions containing metal salts of fatty acids are disclosed in U.S. Pat. No. 3,655,374, the disclosure of which is totally incorporated herein by reference. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplished, reference U.S. Pat. No. 3,635,704, the disclosure of which is totally incorporated herein by reference. Additionally, there are illustrated in U.S. Pat. No. 3,983,045, the disclosure of which is totally incorporated herein by reference, three component developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43.
Other references of interest which disclose toner compositions with various resins, such as amides and the like, include U.S. Pat. Nos. 4,072,521; 4,073,649 and 4,076,641. Furthermore, references of background interest are U.S. Pat. Nos. 3,165,420; 3,236,776; 4,145,300; 4,271,249; 4,556,624; 4,557,991 and 4,604,338.
Moreover, toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There is also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there is illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions; and in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride. Other prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014 and 4,394,430. Many of the aforementioned charge additives can be selected as an optional component for the toner compositions of the present invention as indicated herein.
As a result of a patentability search there were located U.S. Pat. Nos. (1) 3,654,865 which discloses gelatin toners; (2) 4,013,572 and 4,186,003 wherein photogradable toners are described; and (3) 4,105,572 which illustrates water soluble or solubilizable toner resins.
Although the above described toner and developer compositions are useful for their intended purposes, there is a need for improved compositions. More specifically, there is a need for biodegradable toner resin compositions, including single component, and colored toner compositions. There is also a need for biodegradable toner resin compositions comprised of semicrystalline bacterial polyesters, and semicrystalline polyesters obtained with the process of the present invention illustrated herein. In addition, there is a need for toner and developer compositions with semicrystalline polyesters that can be selected for electrophotographic imaging and printing processes. There is also a need for biodegradable toner compositions comprised of biodegradable semicrystalline polyesters that possess many other advantages including a blocking temperature of from about 80.degree. to 180.degree. C., and a minimum fix temperature of from about 200.degree. to about 400.degree. F., and preferably from about 300.degree. to about 350.degree. F. (fuser set temperature). Moreover there is a need for toner polymer resins with superior miscibility with pigments, such as carbon black, acceptable melt rheology characteristics, and which polymers can be readily extrudable. Additionally, there is a need for polymer toner resins that are biodegradable, chemically and/or biologically, thereby enabling deinking thereof. There is also a need for toners with semicrystalline polyesters, which toners provide excellent image quality with low background deposits are of superior fix and permanence. There is also a need for toners with lower fuser energy requirements as compared to, for example, several presently known toner compositions. Moreover, there is a need for an efficient economical synthetic process for the preparation of semicrystalline polyesters. Furthermore, there is a need for encapsulated toners comprised of the cores of biodegradable polyesters illustrated herein.